Students wonder which readings from the professor’s list are really necessary, shoppers are unsure just which items to bring back from the grocery store and worshippers question which commandments from God’s list they really have to observe. This common experience unfortunately also applies when we are sorting out our moral obligations. Since the 17th century, we have increasingly thought of contested moral issues in terms of the rights of the parties involved. These rights are held by individual subjects. Natural or human rights are affirmed for all human beings, regardless of their status, gender, religion, history or individual choices. They express and shape our relations with very important goods in our lives, such as life, liberty, happiness, security, religion and conscience.

For this reason, they usually also have an urgency and a priority over other claims and obligations. But all rights do not have an equal priority. The subject of abortion, one of the longest-running disputes in American society, is commonly put as “right to life” of the fetus, versus “right to choice” of the mother. It’s apparent here that not all rights can prevail.

The language of rights is a powerful instrument for legal and political advocacy and for protecting individuals and communities. But it is not easy to set out a clear or concise account of how to prioritize rights on any universal basis. Now, one promising way of settling the priority question is by establishing that some rights are more basic. But this quickly becomes problematic because there are several ways in which rights can be basic. These include historical priority in being discovered and affirmed by society; necessity in pursuing one’s projects or exercising one’s rights; developmental priority in the life of the individual human subject; valuable in itself, affirmation by social consensus; overwhelming social importance; and organizing principles for our thoughts and decisions.

The project of basing the inviolability of certain rights on their basic or fundamental character becomes more difficult. Catholicism did not originally base its opposition to abortion on a theory of rights or of goods that could never be violated. Rather, it appealed to the value of human life and to the evil of the act of killing a human being.

In this way, it fostered an increasingly universal or “catholic” approach to human community and to the protection of human life. Now, the denial of a right to life to the fetus also denies it all other rights and any place in the human community. It is not merely one restriction or diminishment, it is the rejection of the new being with all its possibilities, needs and claims. The denial of the rights of human beings forms a central element in a long, tragic and sinful history of rejection and exclusion, which has marked most national and religious communities, including Catholicism.

Proponents of abortion are not animated by racial or religious prejudice, though some of them may espouse a right to abortion because of a culturally based preference for males over females or because they fear population pressures and the influx of immigrants from “inferior” cultures or peoples. Principally, they are animated by a concern for the rights and interests of women.

Catholicism, with its emphasis on the embodiment of the human person is willing to trace the unity and individuality of the human person, back to its embryonic beginnings in the fertilization of the ovum by the sperm. The fetus knocks on the door of the human family and asks for admittance as a person. The obligation to welcome and to care for this new member falls primarily on the mother and the father, and then on the community. Far too often the unwed and the poor have been assigned burdens which they cannot meet. In a rightly ordered society, the rights of the fetus are protected by affirming the economic and social rights of the parents.

Catholic social teaching proposes that the young be raised with a sense of human solidarity; Catholic theology affirms that all are to be treated as God’s children; Catholic communities around the world have learned the necessity of respecting the human rights of all. The Church’s defense of the right to life forms part of a larger vision of humanity, which does not find fulfillment in the adversarial relationships of the law court or in the manipulative relations of the market but in the communion of minds and hearts living together with mutual care and respect.

Fr. John Langan, S.J., is a professor of philosophy, Joseph Cardinal Bernardin Professor of Catholic Social Thought and member of the core faculty of the School of Foreign Service.